U.S. patent application number 14/341411 was filed with the patent office on 2015-01-29 for deactivation of microwave interactive material.
The applicant listed for this patent is Graphic Packaging International, Inc.. Invention is credited to William Gilpatrick, Jeffrey T. Sloat.
Application Number | 20150030865 14/341411 |
Document ID | / |
Family ID | 52390760 |
Filed Date | 2015-01-29 |
United States Patent
Application |
20150030865 |
Kind Code |
A1 |
Sloat; Jeffrey T. ; et
al. |
January 29, 2015 |
Deactivation of Microwave Interactive Material
Abstract
Microwave energy interactive material is partially coated with
thermoset polymeric material. The thermoset polymeric material is
cured on a first portion of the microwave energy interactive
material. A second portion of the microwave energy interactive
material is neither covered by nor protected by the cured thermoset
polymeric material. A deactivating agent is applied to the coated
microwave energy interactive material, so that the agent
deactivates the second portion of the microwave energy interactive
material into a microwave energy transparent area. The cured
thermoset polymeric material protects the first portion of the
microwave energy interactive material from the agent, so that it
remains microwave energy interactive.
Inventors: |
Sloat; Jeffrey T.;
(Broomfield, CO) ; Gilpatrick; William;
(Broomfield, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Graphic Packaging International, Inc. |
Atlanta |
GA |
US |
|
|
Family ID: |
52390760 |
Appl. No.: |
14/341411 |
Filed: |
July 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61858775 |
Jul 26, 2013 |
|
|
|
Current U.S.
Class: |
428/472.2 ;
156/182; 427/256; 427/510; 427/511 |
Current CPC
Class: |
B32B 38/00 20130101;
B32B 27/10 20130101; B32B 27/36 20130101; B32B 2307/20 20130101;
B32B 2037/243 20130101; B32B 2553/00 20130101; B32B 2038/0076
20130101; B65D 2581/3489 20130101; B65D 2581/3467 20130101; B32B
2307/412 20130101; B32B 2255/10 20130101; B65D 81/3446 20130101;
B32B 2255/26 20130101; B65D 2581/344 20130101; B32B 37/24 20130101;
B32B 2439/70 20130101; B32B 27/16 20130101; B32B 27/08
20130101 |
Class at
Publication: |
428/472.2 ;
427/256; 427/510; 427/511; 156/182 |
International
Class: |
B65D 81/34 20060101
B65D081/34; B32B 38/00 20060101 B32B038/00; B32B 37/24 20060101
B32B037/24; B05D 3/10 20060101 B05D003/10; B05D 5/00 20060101
B05D005/00; B05D 3/06 20060101 B05D003/06 |
Claims
1. A packaging material, comprising: a substrate; microwave energy
interactive material on the substrate; microwave energy transparent
material on the substrate and adjacent to the microwave interactive
material on the substrate, the microwave energy transparent
material comprising the microwave energy interactive material in a
deactivated condition; and thermoset polymeric material on the
microwave energy interactive material, the thermoset polymeric
material and the microwave energy interactive material being
superposed with one another.
2. The packaging material of claim 1, wherein the deactivated
microwave energy interactive material is not covered by the
thermoset polymeric material.
3. The packaging material of claim 1, wherein the thermoset
polymeric material comprises a UV-cured material.
4. The packaging material of claim 1, wherein a peripheral edge of
an area of the microwave energy interactive material is superposed
with a peripheral edge of the thermoset polymeric material in a
plan view of the packaging material.
5. The packaging material of claim 1, wherein: the substrate has
opposite first and second sides; the microwave energy interactive
material is connected to the first side of the substrate; and the
deactivated microwave energy interactive material is connected to
the first side of the substrate.
6. The packaging material of claim 1, wherein the deactivated
microwave energy interactive material comprises aluminum oxide.
7. The packaging material of claim 1, wherein: the substrate is a
first substrate; the packaging material further comprises a second
substrate; and each of the microwave energy interactive material,
the deactivated microwave energy interactive material, and the
thermoset polymeric material is positioned between the first and
second substrates.
8. The packaging material of claim 7, wherein: the first substrate
comprises a polymeric film; and the second substrate comprises
paper.
9. The packaging material of claim 8, wherein the paper is
paperboard.
10. The packaging material of claim 1, wherein: at least a portion
of the substrate extends in a first plane; at least a portion of
both the microwave energy interactive material and the deactivated
microwave energy interactive material extend in a second plane, so
that at least a portion of the microwave energy interactive
material and at least a portion of the deactivated microwave energy
interactive material are coplanar; and the first and second planes
are parallel to one another.
11. The packaging material of claim 10, wherein: at least a portion
of the thermoset polymeric material extends in a third plane; and
the first, second and third planes are parallel to one another.
12. The packaging material of claim 11, wherein: the substrate is a
first substrate; the packaging material further comprises a second
substrate; each of the microwave energy interactive material, the
deactivated microwave energy interactive material, and the
thermoset polymeric material is positioned between the first and
second substrates; at least a portion of the second substrate
extends in a fourth plane; and the first, second, third and fourth
planes are parallel to one another.
13. A method of at least forming a microwave energy transparent
area in a layer of microwave energy interactive material, the
method comprising: partially coating the layer of microwave energy
interactive material with thermoset polymeric material, comprising
curing the thermoset polymeric material on a first portion of the
layer of microwave energy interactive material so that the cured
thermoset polymeric material is operative to protect the first
portion of the layer of microwave energy interactive material, and
a second portion of the layer of microwave energy interactive
material is neither covered by nor protected by the cured thermoset
polymeric material; applying an agent to the coated layer of the
microwave energy interactive material, so that the agent transforms
the second portion of the layer of microwave energy interactive
material into a microwave energy transparent area, and the cured
thermoset polymeric material protects the first portion of the
layer of microwave energy interactive material from the agent, so
that the first portion of the layer of microwave energy interactive
material remains microwave energy interactive.
14. The method of claim 13, wherein: the agent is a deactivating
agent, and the deactivating agent deactivates the second portion of
the layer of microwave energy.
15. The method of claim 13, wherein: the partially coating is
comprised of applying the thermoset polymeric material to the first
portion of the layer of microwave energy interactive material,
prior to the curing of the thermoset polymeric material; and the
curing of the thermoset polymeric material is comprised of curing
the thermoset polymeric material with ultraviolet light.
16. The method of claim 15, wherein the applying of the thermoset
polymeric material is comprised of printing the thermoset polymeric
material onto the first portion of the layer of microwave energy
interactive material.
17. The method of claim 13, wherein: the layer of microwave energy
interactive material is part of a laminate that further comprises a
substrate; the layer of microwave energy interactive material has
opposite first and second sides; the first side of the layer of
microwave energy interactive material is mounted to the substrate;
and the partially coating is comprised of partially coating the
second side of the layer of microwave energy interactive material
with the thermoset polymeric material.
18. The method of claim 17, wherein: the substrate is a first
substrate; and the method further comprises laminating a second
substrate to the laminate so that at least each of the cured
thermoset polymeric material and the first portion of the layer of
microwave energy interactive material is positioned between the
first and second substrates.
19. The method of claim 18, wherein: the first substrate comprises
a polymeric film; and the second substrate comprises paper.
20. A method of at least forming a microwave energy transparent
area in a layer of microwave energy interactive material, the
method comprising: partially coating the layer of microwave energy
interactive material with thermoset polymeric material, comprising
printing the thermoset polymeric material onto a first portion of a
layer of microwave energy interactive material; curing the
thermoset polymeric material on the first portion of the layer of
microwave energy interactive material, comprising exposing the
thermoset polymeric material on the first portion of the layer of
microwave energy interactive material to ultraviolet light, so that
the cured thermoset polymeric material is operative to protect the
first portion of the layer of microwave energy interactive
material, and a second portion of the layer of microwave energy
interactive material is neither covered by nor protected by the
cured thermoset polymeric material; applying a deactivating agent
to the coated layer of the microwave energy interactive material,
so that the agent deactivates the second portion of the layer of
microwave energy interactive material into a microwave energy
transparent area, and the cured thermoset polymeric material
protects the first portion of the layer of microwave energy
interactive material from the agent, so that the first portion of
the layer of microwave energy interactive material remains
microwave energy interactive.
21. The method of claim 20, wherein: the layer of microwave energy
interactive material is part of a laminate that further comprises a
substrate; the layer of microwave energy interactive material has
opposite first and second sides; the first side of the layer of
microwave energy interactive material is mounted to the substrate;
and the partially coating is comprised of partially coating the
second side of the layer of microwave energy interactive material
with the thermoset polymeric material.
22. The method of claim 21, wherein: the substrate is a first
substrate; and the method further comprises laminating a second
substrate to the laminate so that at least each of the cured
thermoset polymeric material and the first portion of the layer of
microwave energy interactive material is positioned between the
first and second substrates.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/858,775, filed Jul. 26, 2013, the entire
contents of which are incorporated herein by reference.
BACKGROUND
[0002] Microwave ovens provide a convenient means for heating a
variety of food items. It is common for the food being heated to be
contained by a package comprising microwave energy interactive
material ("MEIM") mounted to a substrate that is transparent to
microwave energy. The MEIM may be discontinuous to achieve the
desired heating effect of the food item. For example, the MEIM may
be discontinuous by virtue of the MEIM defining a pattern. Examples
of discontinuous MEIM and associated manufacturing methods are
disclosed in prior U.S. Patents.
[0003] As a more specific example regarding packaging material in
which the MEIM is aluminum that is mounted to a polymer film, it is
known to patternize the aluminum in order to achieve a desired
heating effect in a microwave oven. For example, it is known to use
a rotogravure printing press to apply a pattern of solvent-based
resist coating to a continuous layer of aluminum ("precursor
aluminum") that was previously mounted to and is being carried by
the polymer film. The solvent-based resist coating is applied in
the same pattern that is intended to be defined by the resultant
patternized aluminum.
[0004] After printing, the solvent-based resist coating is dried by
evaporating its solvent. The web is then drawn through a caustic
bath of 50% sodium hydroxide. The resist coating is resistant to
the caustic bath so that the caustic bath does not react with the
protected portion of the aluminum, wherein the protected portion of
the aluminum is superposed with the resist coating. In contrast,
the caustic bath reacts with the unprotected portion of the
aluminum, wherein the unprotected portion of the aluminum is not
superposed with the resist coating. The caustic bath deactivates
the unprotected portion of the aluminum by converting it to
aluminum oxide. The aluminum oxide is relatively transparent to
light as compared to pure aluminum. In further contrast to
aluminum, aluminum oxide is an electrical insulator that is
transparent to microwave energy.
[0005] The web is rinsed with water immediately after the web is
drawn out of the caustic bath. The web is then wet-bond laminated
to paperboard to create packaging material. The aluminum, aluminum
oxide and resist coating are positioned between the paperboard and
the polymer film in the packaging material
[0006] The above-described step of evaporating the solvent of the
solvent-based resist coating may be a limiting factor in the
manufacturing of the packaging material. There is a desire for
improvements to manufacturing line speeds, efficiency, quality
and/or over-all costs.
BRIEF SUMMARY
[0007] An aspect of this disclosure is the provision of a method
for at least forming a microwave energy transparent area in a layer
of microwave energy interactive material ("MEIM"). The method may
include partially coating the layer of MEIM with thermoset
polymeric material. For example, the thermoset polymeric material
may be printed onto a first portion of the layer of MEIM. Then, the
thermoset polymeric material on the first portion of the layer of
MEIM may be cured, for example, by exposure to ultraviolet ("UV")
light. That is, the thermoset polymeric material may advantageously
be a UV-cured material. The cured thermoset polymeric material is
for protecting the first portion of the layer of MEIM. In contrast,
a second portion of the layer of MEIM is neither covered by nor
protected by the cured thermoset polymeric material. The method may
further include applying an agent to the coated layer of the MEIM,
so that the agent transforms the second portion of the layer of
MEIM into a microwave energy transparent area. In contrast, the
cured thermoset polymeric material is for protecting the first
portion of the layer of MEIM from the agent, so that the first
portion of the layer of MEIM remains microwave energy interactive.
For example, the agent may be a deactivating agent, so that the
deactivating agent deactivates the second portion of the layer of
MEIM.
[0008] The first portion of the layer of MEIM, which remains
microwave energy interactive, may be referred to as resultant MEIM.
The microwave energy transparent area, or more specifically the
second portion of the layer of MEIM, which was deactivated, may be
referred to as deactivated MEIM. Each of the resultant and
deactivated MEIMs may be arranged in a pattern.
[0009] The resultant and deactivated MEIMs may both be parts of a
packaging material that further includes a substrate. The resultant
and deactivated MEIMs may be connected to the substrate, such as by
a layer of adhesive material. The resultant and deactivated MEIMs
may be adjacent to one another on the substrate. The packaging
material may further include the thermoset polymeric material in a
superposed configuration with the resultant MEIM. The thermoset
polymeric material of the packaging material is typically
transparent to microwave energy. In an embodiment of this
disclosure, the deactivated MEIM is not covered by the thermoset
polymeric material.
[0010] The substrate of the packaging material may be a first
substrate, and the packaging material may further include a second
substrate, so that the thermoset polymeric material and the
resultant and deactivated MEIMs are positioned between the first
and second substrates. The first substrate may be a polymeric film,
and the second substrate may be paper, such as paperboard. The
packaging material may be configured in any suitable conventional
manner.
[0011] In one aspect of this disclosure, the deactivated MEIM may
be referred to as microwave energy transparent material.
[0012] The foregoing presents a simplified summary of some aspects
of this disclosure in order to provide a basic understanding. The
foregoing is not an extensive summary and is not intended to
identify key or critical elements of the invention or to delineate
the scope of the invention. The purpose of the foregoing summary is
to present some concepts of this disclosure in a simplified form as
a prelude to the more detailed description that is presented later.
For example, other aspects will become apparent from the
following.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the following, reference is made to the accompanying
drawings, which are schematic and not drawn to scale. The drawings
are exemplary only, and should not be construed as limiting the
inventions.
[0014] FIG. 1 illustrates a system and method for forming packaging
material, in accordance with a first embodiment of this
disclosure.
[0015] FIG. 2 illustrates a section of the packaging material of
FIG. 1, in accordance with an embodiment of this disclosure.
[0016] FIG. 3 is a cross-sectional view of a portion of the
packaging material of FIG. 2 taken along line 3-3 of FIG. 2, in
accordance with an embodiment of this disclosure.
DETAILED DESCRIPTION
[0017] Exemplary embodiments are described below and illustrated in
the accompanying drawing, in which like numerals refer to like
parts. The embodiments described provide examples and should not be
interpreted as limiting the scope of the invention. Other
embodiments, and modifications and improvements of the described
embodiments, will occur to those skilled in the art and all such
other embodiments, modifications and improvements are within the
scope of the present invention. For example, features illustrated
or described as part of one embodiment can be used in the context
of another embodiment to yield a further embodiment, and these
further embodiments are within the scope of the present
invention.
[0018] A system for forming a laminated packaging material 10 is
illustrated in FIG. 1 and described in the following, in accordance
with a first embodiment. Generally described, a conventional
precursor web 12 is supplied, such as by drawing the precursor web
from a roll 14. The precursor web 12 is transformed into a
resultant web 16 in the manner discussed below. The packaging
material 10 may be the resultant web 16 in isolation, or the
packaging material may comprise the resultant web in combination
with an optional substrate 18 and/or other suitable features, as
will be discussed in greater detail below. That is, and in
accordance with one embodiment of this disclosure, the resultant
web 16 is a packaging material. In the first embodiment, each of
the resultant web 16 and packaging material 10 is a laminate.
[0019] The precursor web 12 comprises, consists of or consists
essentially of microwave energy interactive material 20 ("MEIM")
mounted to a primary substrate 24 that supports the MEIM and is
typically transparent to microwave energy. The primary substrate 24
may be a polymeric film 24 that may comprise, consist of or consist
essentially of polyethylene terephthalate, or any other suitable
polymeric material may be used, as discussed in greater detail
below.
[0020] In the first embodiment, the MEIM 20 is operative for
reflecting a substantial portion of impinging microwave energy
(sometimes referred to as a microwave energy shielding element).
For example, the MEIM 20 may be configured as a patch of metal foil
having a thickness of from about 5 to about 10 micrometers, for
example, about 7 micrometers. Such foil is typically formed from a
conductive, reflective metal or metal alloy, for example, aluminum,
copper, or stainless steel, but other suitable materials may be
used. As a more specific example, the MEIM 20 may be a layer of
aluminum foil that is mounted to the substrate 24 in a conventional
manner. Specifically, the precursor web 12 may be a laminate
comprising the MEIM 20 and the primary substrate 24 joined to one
another by way of adhesive material 19 (FIG. 3). In the first
embodiment, the MEIM 20 is on the primary substrate 24, and more
specifically the MEIM 20 is connected or mounted to the primary
substrate 24 by way of the adhesive material 19, although the
connecting or mounting may be provided in any other suitable
manner.
[0021] Alternatively, the MEIM 20 may be a high (greater than about
1.0) optical density evaporated material having a thickness of from
about 300 to about 700 or more angstroms. For example, the
precursor web 12 may be formed by depositing the MEIM 20 either
directly or indirectly onto the primary substrate 24, such as by
way of vacuum deposition or in any other suitable manner. More
generally, the MEIM 20 may be mounted to the primary substrate 24
in any suitable manner.
[0022] The MEIM-side 20 of the precursor web 12 is selectively
coated in a predetermined manner with a thermoset polymeric resist
coating 26 by drawing the precursor web past or through at least
one coater 28. In the first embodiment, the thermoset polymeric
resist coating 26 may be an ultraviolet-curable ("UV-curable")
resist coating 26. The coater 28 may any suitable coater for
depositing the UV-curable resist coating 26 in any suitable
discontinuous arrangement (e.g., pattern). In FIG. 1, the coater 28
is schematically shown as being a conventional rotogravure printing
press 28. Alternatively, the coater 28 may be other suitable types
of coaters, such as a flexographic printing press. Thus and for
example, the UV-curable resist coating 26 may be a suitable
UV-curable ink, such as a suitable conventional UV-curable ink that
is transparent to microwave energy.
[0023] In the example of FIG. 1, the conventional gravure press 28
includes an impression roller 30 and a printing cylinder 32 between
which the precursor web 12 is nipped. The UV-curable resist coating
26 is contained in and supplied to the printing cylinder 32 from an
upwardly open container or fountain 36 of the press 28. A
conventional doctor blade 38 is associated with the printing
cylinder 32 and fountain 36 in a conventional manner.
[0024] In the first embodiment: the UV-curable resist coating 26
has a viscosity suitable for allowing the UV-curable resist coating
to be printed for facilitating the disclosed method of the first
embodiment; the MEIM 20 of the precursor web 12 is a continuous
layer of aluminum 20 ("precursor aluminum") that is sufficiently
thick for reflecting impinging microwave energy; and the coater 28
prints the UV-curable resist coating 26 directly onto the outer
face of the aluminum 20 in a pattern. The printed pattern is the
same as (e.g., substantially the same as) the pattern of the
resultant patternized aluminum of the resultant web 16.
[0025] The UV-curable resist coating 26 printed on the MEIM 20 is
cured by drawing the coated web 12 in sufficiently close proximity
to and past at least one ultraviolet ("UV") light source 40. The UV
light source(s) 40 may be conventional. The UV light source(s) 40
cause the UV-curable resist coating 26 printed on the MEIM 20 to
become a cured thermoplastic resist coating 41. As should be
apparent from the foregoing, the cured thermoplastic resist coating
41 may be a UV-cured resist coating 41. The UV-cured resist coating
41 is adhered to and carried by the MEIM-side 20 of the web 12.
[0026] The UV-curable resist coating 26 is typically immediately
(e.g., substantially immediately) cured after the printing by
exposure to the UV energy provided by the at least one UV light
source 40. The UV-curable resist coating 26 is typically exposed to
sufficient UV energy from the UV light source(s) 40 so that the
UV-curable resist coating 26 is immediately (e.g., substantially
immediately) cured (e.g., substantially fully cured) as soon as the
UV-curable resist 26 coating is carried past the UV light source(s)
40 by the traveling web 12. Typically, as soon as the UV-curable
resist coating 26 is fully cured by passing the UV light source(s)
40, the resulting UV-cured resist coating 41 is nearly or
approximately (e.g., substantially) 100% solids so that the
UV-cured resist coating typically does not include any solvent that
has to be dried (e.g., evaporated). Due to the lack of drying and
the relatively quick speed of curing of the UV-curable resist
coating 26, it is believed that the use of the UV-curable resist
coating 26 will increase manufacturing speeds as compared to the
use of solvent-based resist coatings. In the first embodiment, the
UV-cured resist coating 41 is transparent to microwave energy. In
an alternative embodiment, the precursor web 12 may consist solely
of the MEIM 20, wherein the MEIM may be in the form of a metallic
foil, and the metallic foil with the UV-cured resist coating 41
thereon may be referred to as a laminate.
[0027] After formation of the UV-cured resist coating 41, the
coated web 12 is drawn through, or otherwise exposed to, a caustic
dispersion 42 that may be contained in an upwardly open container
44 (e.g., a caustic bath). In the first embodiment, the UV-cured
resist coating 41 is sufficiently resistant to the caustic
dispersion 42 (e.g., 50% sodium hydroxide dispersion) so that the
caustic dispersion does not react with the protected portion of the
MEIM 20, wherein the protected portion of the MEIM is adhered to
and superposed with the UV-cured resist coating 41. In contrast,
the caustic dispersion 42 reacts with the unprotected portion of
the MEIM 20, wherein the unprotected portion of the MEIM is neither
adhered to nor superposed with the UV-cured resist coating 41. When
the MEIM 20 is aluminum, the caustic dispersion 42 typically
deactivates the unprotected portion of the aluminum by converting
it to aluminum oxide, wherein the aluminum oxide is the MEIM (e.g.,
aluminum) in a deactivated condition. The aluminum oxide is
relatively transparent to light as compared to pure aluminum. In
contrast to aluminum, aluminum oxide is an electrical insulator
that is transparent to microwave energy.
[0028] Optionally and depending upon factors such as the strength
of the caustic dispersion 42 and the duration of the exposure
thereto, at least some of the aluminum oxide may be etched away or
otherwise removed from the web 12. The caustic dispersion 42 may be
more generally referred to as an agent, or a deactivating agent.
Examples of suitable deactivating agents are disclosed in U.S. Pat.
No. 4,865,921, which is incorporated herein by reference in its
entirety.
[0029] As the web 12 is drawn out of the caustic bath 44, the web
typically carries some of the caustic dispersion 42. The web 12 is
then drawn through or past a conventional rinsing station 46. In
the rinsing station 46, the web 12 is rinsed with water and/or one
or more other fluids, or the like, so that the resultant web 16
(e.g., laminate) is absent of (e.g., substantially absent of) any
caustic dispersion 42.
[0030] The resultant web 16 comprises the precursor web 12 (e.g.,
polymeric film), a pattern of resultant MEIM 50 (e.g., aluminum), a
pattern of deactivated MEIM 52 (e.g., aluminum oxide) and the
UV-cured resist coating 41. The pattern of the resultant MEIM 50 of
the resultant web 16 corresponds to, and is superposed with, the
pattern of the UV-cured resist coating 41 of the resultant web.
Examples of patterns of the resultant MEIM 50 in the resultant web
16 are discussed in greater detail below. Any other suitable
patterns of the resultant MEIM 50, such as any suitable
conventional patterns, are also within the scope of this
disclosure.
[0031] The resultant web 16 may be drawn through or past a
conventional lamination station 60, wherein the resultant web may
be laminated (e.g., wet-bond laminated) to the substrate 18 (e.g.,
paper, or more specifically paperboard) to create the packaging
material 10. The substrate 18 may be drawn from a roll, and the
packaging material 10 may be formed into another roll. In the
packaging material 10, the resultant MEIM 50, deactivated MEIM 52
(e.g., microwave energy transparent material) and UV-cured resist
coating 41 are typically positioned between the additional
substrate 18 and the primary substrate 24. The laminating at the
lamination station 60 may comprise joining the resultant web 16 and
the substrate 18 to one another by way of adhesive material 62
(FIG. 3), wherein the this joining together may be carried out in a
conventional manner.
[0032] FIG. 2 schematically illustrates a lengthwise section of the
packaging material 10 and provides an example of one of the
numerous possible configurations or patterns of the resultant MEIM
50, deactivated MEIM 52 (e.g., microwave energy transparent
material) and
[0033] UV-cured resist coating 41 (FIGS. 1 and 3). In FIG. 2, the
primary substrate 24 (FIGS. 1 and 3) is facing upward and
transparent, so that the resultant MEIM 50 is seen through the
transparent primary substrate. Similarly, the deactivated MEIM 52
(FIGS. 1 and 3) is transparent in FIG. 2. The UV-cured resist
coating 41 is hidden from view beneath the resultant MEIM 50 in
FIG. 2. In FIG. 2, the UV-cured resist coating 41 and resultant
MEIM 50 are shaped to form first and second sections 152, 252 of
the resultant MEIM 50. The first section 152 of the resultant MEIM
50 or the second sections 252 of the resultant MEIM 50 may be
omitted and/or configured differently than shown in FIG. 2.
[0034] As shown in FIG. 2, the first section 152 of the resultant
MEIM 50 is in the form of a metal foil band including somewhat
rounded corners 104 and obround holes 106 in the MEIM 50, wherein
the holes are in a spaced apart configuration. As used in this
Detailed Description section of this disclosure, the term "obround"
refers to a shape substantially consisting of two semicircles
connected by parallel lines tangent to their endpoints. The first
section 152 of the resultant MEIM 50 may be referred to as a
microwave energy reflecting (or reflective) element that may be
used as a shielding element when an associated food item is prone
to scorching or drying out during heating in a microwave oven. More
specifically, at least portions of the resultant MEIM 50 together
with the deactivated MEIM 52 in the holes 106 may be cooperative,
such for diffusing or lessening the intensity of microwave energy,
such as when these features are parts of upright walls of a tray.
One example of a material utilizing a combination of such microwave
energy reflecting and transparent elements is commercially
available from Graphic Packaging International, Inc. (Marietta,
Ga.) under the trade name MicroRite.RTM. packaging material.
[0035] The second sections 252 of the resultant MEIM 50 are in the
form of metal foil segments 110 arranged in clusters in a
lattice-like configuration. Only a few of the foil segments 110 are
identified by their reference numeral in FIG. 2. The first section
152 of the resultant MEIM 50 is spaced from and forms a border
around the second sections 252 of the resultant MEIM 50. The second
sections 252 of the resultant MEIM 50 may comprise a plurality of
microwave energy reflecting elements arranged to form a microwave
energy distributing element that is operative for directing
microwave energy to specific areas of an associated food item. If
desired, the loops defined by the second sections 252 of the
resultant MEIM 50 may be of a length that causes microwave energy
to resonate (e.g., a resonating patch antenna), thereby enhancing
the distribution effect. Examples of microwave energy distributing
elements are described in U.S. Pat. Nos. 6,204,492, 6,433,322,
6,552,315, and 6,677,563, each of which is incorporated by
reference in its entirety.
[0036] In the embodiment shown in FIGS. 2 and 3, and more
specifically in a top plan view similar to FIG. 2, adjacent to each
annular deactivated area of MEIM 52 (e.g., microwave energy
transparent material), an annular peripheral edge of the resultant
MEIM 50 is superposed with an annular peripheral edge of the
UV-cured resist coating 41. In the embodiment shown in FIG. 3,
layers 18, 19, 24, 41, 50, 52, 62 that are respectively adjacent to
one another are more specifically in opposing face-to-face contact
with one another. In other embodiments, one or more other layers
may be respectively positioned between one or more pairs of the
layers 18, 19, 24, 41, 50, 52, 62 that are adjacent to one another
in FIG. 3. The portion of the packaging material 10 shown in FIG. 3
is in a flat configuration, so that the resultant and deactivated
MEIMs 50, 52 are coplanar, and the layers 18, 19, 24, 41, 50, 52,
62 respectively extend in planes that are parallel to one
another.
[0037] At least partially reiterating from above, it is within the
scope of this disclosure for the resultant web 16 to be in the form
of, and to be used as, packaging material. In this regard and in
accordance with an embodiment of this disclosure, the packaging
material 10, 16 may be formed into, or otherwise incorporated into,
any suitable packages, such as cartons, trays, wraps, bags, or the
like. Food products to be heated in microwave ovens may be
contained in or otherwise associated with the packages. The
substrate-side 24 (e.g., polymeric film side) of the precursor web
12 will typically be the interior surface of packages formed from
the packaging material 10, 16. However, a variety of differently
configured packaging materials and packages are within the scope of
this disclosure.
[0038] As nonlimiting examples, the primary substrate 24 may be a
polymeric film having a thickness from about 35 gauge to about 10
mil. The thickness of the polymeric film may be from about 40 to
about 80 gauge, from about 45 to about 50 gauge, or about 48 gauge.
Examples of polymeric films that may be suitable include, but are
not limited to, polyolefins, polyesters, polyamides, polyimides,
polysulfones, polyether ketones, cellophanes, or any combination
thereof Reiterating from above, the polymeric film may comprise
polyethylene terephthalate. Examples of polyethylene terephthalate
film that may be suitable for use as the primary substrate 24
include, but are not limited to, MELINEX.RTM., commercially
available from DuPont Teijan Films (Hopewell, Va.), and SKYROL,
commercially available from SKC, Inc. (Covington, Ga.).
Polyethylene terephthalate films are used in commercially available
packaging materials, for example, MicroRite.RTM. packaging material
available from Graphic Packaging International. Other
non-conducting primary substrate 24 materials such as paper and
paper laminates, metal oxides, silicates, cellulosics, or any
combination thereof, also may be used.
[0039] The resultant web 16 (e.g., laminate) may be laminated or
otherwise joined to another material, such as, but not limited to,
the substrate 18, or a surface of a wall of a package or other
suitable structure. In one example, the resultant web 16 may be
laminated or otherwise joined to a substrate 18 in the form of
paper or paperboard. The paper may have a basis weight of from
about 15 to about 60 lb./ream (lb./3000 sq. ft.), for example, from
about 20 to about 40 lb./ream, for example, about 25 lb./ream. The
paperboard may have a basis weight of from about 60 to about 330
lb./ream, for example, from about 80 to about 200 lb./ream. The
paperboard generally may have a thickness of from about 6 to about
30 mils, for example, from about 12 to about 28 mils. In one
particular example, the paperboard has a thickness of about 20 mils
(0.020 inches). Any suitable paperboard may be used, for example, a
solid bleached sulfate board, for example, Fortress.RTM. board,
commercially available from International Paper Company, Memphis,
Tenn., or solid unbleached sulfate board, such as SUS.RTM. board,
commercially available from Graphic Packaging International.
[0040] If desired, the resultant web 16 or packaging material 10
may further include or otherwise be used in conjunction with other
microwave energy interactive elements and/or structures such as,
but not limited to, one or more susceptor layers (e.g. layers of
aluminum) configured for absorbing at least a portion of impinging
microwave energy and converting it to thermal energy (i.e., heat)
through resistive losses in the layer of aluminum, or the like.
Alternatively, the MEIM 20 and resultant MEIM 50 may be
sufficiently thin for functioning as susceptors that absorb at
least a portion of impinging microwave energy and convert it to
thermal energy (i.e., heat) through resistive losses.
[0041] The above-disclosed patterns (e.g., of the resist coating
26, resultant MEIM 50, deactivated MEIM 52, and first and second
sections 152, 252) are provided as examples only, and other
patterns are within the scope of this disclosure. For example, one
or more of the above-disclosed patterns may be tailored to the
desired end uses of the packaging materials 10 and 16, or the
like.
[0042] The above examples are in no way intended to limit the scope
of the present inventions. It will be understood by those skilled
in the art that while the present disclosure has been discussed
above with reference to exemplary embodiments, various additions,
modifications and changes can be made thereto without departing
from the spirit and scope of the inventions, some aspects of which
are set forth in the following claims.
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